Okay, so we started on punnet squares and such in Biology. I understand how to to it when I only have one gene from each parent, but what about two? When I work it, I get an answer that (in my ignorance) doesn't really make much sense.

Say, for example, I have a heterozygous tall (Tt), purple-flowered (Pp) plant crossed with a short(tt), white-flowered (pp) plant. When I do the square, I get the possibilities of Pptt, Pppp, Tttt, and Ttpp. But this doesn't look right to me, because one of them does not have a specified flower color (Tttt), and another result does not have the height specified (Pppp). I am attempting to find the phenotype, and I have no idea what I would say with these results. I cannot ask my teacher, as we're on vacation. My textbook doesn't go any further than one gene from each parent. What am I doing wrong?

airshipBN77 wrote:Okay, so we started on punnet squares and such in Biology. I understand how to to it when I only have one gene from each parent, but what about two? When I work it, I get an answer that (in my ignorance) doesn't really make much sense.

Say, for example, I have a heterozygous tall (Tt), purple-flowered (Pp) plant crossed with a short(tt), white-flowered (pp) plant. When I do the square, I get the possibilities of Pptt, Pppp, Tttt, and Ttpp. But this doesn't look right to me, because one of them does not have a specified flower color (Tttt), and another result does not have the height specified (Pppp). I am attempting to find the phenotype, and I have no idea what I would say with these results. I cannot ask my teacher, as we're on vacation. My textbook doesn't go any further than one gene from each parent. What am I doing wrong?

Three answers and noone says, how to do it actually shame on you!

OK, you get one plant TtPp and the other ttpp. So, in first case, you can combine any of T or t and P or p, that is TP, Tp, tP, tp In the other case, you can get only tp, so now just combine all cases from each, that isTtPp, Ttpp, ttPp, ttpp

When you set up a punnet square to find out the various outcomes, the allelic combination in the gametes should be properly mentioned.Here TtPp the heterozygous parent forms 4 types of gametes- TP, Tp, tP and tp; whereas the other parent with genotype ttpp forms only one type of gamete- tp.So now put the punnet cross with: TP, Tp, tP, tp x tpYou will get the following :1 TtPp: 1Ttpp: 1 ttPp: 1 ttppwhich is nothing but 1 tall purple: 1 tall white: 1 short purple: 1 short white.